1. Field of the Invention
The present invention relates to a low viscosity, high gel strength protein-starch composition, a meat emulsion containing the same, and a process for producing the protein-starch composition and meat emulsion. More particularly, the present invention relates to a protein-starch composition containing a complex of a protein material and a starch where the starch is substantially in its native nongelatinized conformation, and a meat emulsion containing the same.
2. Description of the Related Art
Protein materials are widely used to supplement meat products since meat is more scarce worldwide, and much more expensive, than protein materials, which are relatively abundant. For example, soy protein materials such as soy isolates and soy concentrates are commonly used as meat analogs or as meat extenders. The protein materials may be used in several forms of meat products, for example, a protein material may be mixed with ground meat to form meat patties useful for hamburgers, meat loafs, or other minced meat applications, or a protein material may be mixed with meat and stuffed into casings to form frankfurters, sausages, or similar products.
Protein materials may be combined with plant components to reduce the cost of producing meat emulsions from the protein materials and to provide meat emulsions having improved meat-like characteristics. For example, wheat flour may be co-dried with a vegetable protein material such as soy protein isolate to form a composition useful as a meat extending component in a pet food emulsion which provides gel strength to the emulsion upon pasteurization.
Carbohydrates from plant materials are commonly used with protein materials to provide desirable characteristics to the protein materials and meat emulsions containing such protein materials. Starch is a particularly useful carbohydrate for use in combination with protein materials since starch is abundant and can improve the texture and taste of meat emulsions formed with a supplemental protein material.
Meat emulsions containing a protein material blended with starch have improved moisture and fat absorbing characteristics, which lead to improved taste and tenderness upon cooking the meat emulsion. In a study comparing the moisture retaining capacity of soy protein and a filler material formed of cold-blended soy protein and starch, the filler material was found to have a higher moisture retaining capacity, and, therefore, was determined to be the preferred material for forming meat emulsions. I. Rogov & V. Dianova, Study of the Hygroscopic Properties of Meat and Meat Products, Myasnaya Industriya SSSR, No. 12, pp. 29-31 (1978).
Dry-blended or cold-blended protein and starch mixes, while providing desirable moisture and fat absorbing characteristics in a meat emulsion, provide relatively poor gel strength and emulsion stability to a meat emulsion even after the emulsion is cooked. Gel strength and emulsion stability are desirable in a meat emulsion so the meat emulsion has a firm meat-like texture with a stable protein and moisture level.
A starch-protein complex having an improved gel strength and emulsion stability is disclosed in U.S. Pat. No. 4,159,982 to Hermansson. The starch-protein complex is formed by heating starch with an aqueous dispersion of casein at a temperature above the gelation temperature of the starch. The casein protein forms a complex with gelatinized starch granules. The degree of gel strength of the complex is greater than that of the casein itself and the emulsion stability of the protein is improved.
Gelatinization of starch in the presence of protein to form a protein-starch complex, while improving the gel strength and emulsion stability of the protein, excessively increases the viscosity of the complex relative to a dry-blend of the protein and starch, as well as that of a meat emulsion material containing the complex relative to a meat emulsion containing a dry or cold-blended mixture of protein and starch. Processing the high viscosity protein-starch complex into a meat emulsion, and processing the resulting high viscosity meat emulsion material is difficult and expensive on a commercial scale since the high viscosity materials do not flow easily.
What is needed, therefore, is a process for forming a low viscosity protein-starch composition and meat emulsion containing the same which have a high gel strength and emulsion stability upon being cooked.